Summary:

- The Montreal Protocol, an international agreement to protect the ozone layer, has had an unexpected benefit - it has helped reduce air pollution.
- Satellites have been able to monitor the decline in certain air pollutants like chlorofluorocarbons (CFCs) and other ozone-depleting substances since the protocol was implemented in 1989.
- The reduction in these pollutants has led to improved air quality in many parts of the world, demonstrating the positive impact of international cooperation on environmental issues.